Process and apparatus for the cracking of hydrocarbon oils



Aug. 13, 1929. c, w GRAY 1,724,760

PROCESS AND APPARATUS FOR THE CRACKING OF HYDROCARBON OILS Filed Oct. 28, 1924 awventoz w. 1% $91 1, M7/ W MW Patented Aug. 13, 1929.

UNITED STATES 1,724,760 PATENT OFFICE.

GEORGE WILLIAM GRAY, OF NEW YORK, N. Y., ASSIGNOR, BY MESNE ASSIGNMENTS,

TO THE TEXAS COMPANY, OF NEW YORK, N. Y., A CORPORATION OF IOELAWARE.

PROCESS AND APPARATUS FOR THE CRACKING OI HYDROCARB ON OILS.

Application filed October 28, 1924. Serial No. 746,298.-

Ths invention relates to methods and apparatus for making condensible light oils, such as gasoline and naphtha. More particularly it relates to certain novel improvements in the cracking of hydrocarbons whereby higher boiling hydrocarbon oils are decomposed into those of lower boiling point.

One of the object-sot the invention is to provide a substantially continuous cracking process wherein there is a material saving of heat energy which effectively reduces the cost of operation.

Another object of the invention is to progressively charge a given or determinable quantity of oil through successive stages of cracking under varying conditions until the maximum quantity of light oil has been obtained from the initial or original charge.

Another object of the invention is to conservein so far as possible such heat as may, from time to time, through the successive stages of the process, be" applied to the oil, so that the self contained heat may be utilized to effect a saving of external heat required to bring about cracking in the several cracking zones.

Yet another object of the invention is to introduce fresh charges of oil having specific characteristics into certain of the cracking zones as may be required or desired.

A still further-object of the invention is to provide'suitable apparatus for carrying out the herein described process or method of cracking heavyhydrocarbons.

These and other objects and advantages of the invention will more readily appearexternally by means of a furnace in a well known manner. The still 10 is connected by means of a charging line 13, with a suitable source of oil supply from which the charging example, conveniently take the form of bub-l ble towers. The separating devices are severallyprovided with vapor lines 21, 22 and 23, respectively, extending to suitable condensers 2st, 25 and 26, respectively, in which the low boiling fractions are condensed and from which they may be drawn off in the form of distillate and utilized or stored in tanks 27, 28 and 29, respectively, as desired. The lines 30, 31 and 32 connecting the condensers 24, 25 and 26 and storage tanks 27, 28 and 29 are branched, the branches 36, 37 and 38 leading back to the separating devices 18, 19 and 20, respectively, for the purpose of returning'some of the distillate. Suitable valves such as 33 and 34. are provided in the main lines 30, 31 and 32 and in the branch lines 36, 37 and 38 respectively, so that all or any part of the distillate may be charged into the tanks provided for the purpose or refluxed to the condensers 18, 19 and 20, as may be desirable or necessary.

The separating .devices 18, 19 and 20 are provided with lines or pipes 39,40 and 41,

respectively, which connect the lower portions of the separating devices with the next succeeding still of the series, except that in the case of the last separating device of the series the condensate therein may be disposed of in any desired way. The lines or pipes 39 and 40 are each covered or insulated to prevent loss of heat from the condensate passing therethrough. 'Each of these lines is also provided with suitable pumping means 42 and 43 respectively, adapted to pump hot oil, and for this purpose a surge pump, if desired, may be employed.

Briefly stated, the process,-as' so far described is as follows Oil, such as gas oil, is pumped into the still 10 which, for example, may be operating under a temperature of approximately 7 50 F. and a pressure of about 150 lbs. At that temperature and pressure cracking of the higher boiling fractions takes place and the vapors evolved will pass to the separating device 18 wherein the high boiling fractions are separated from those of lower boiling point. The. low boiling gasoline-like fractions, still in the form of vapors, pass through the separating device and on to the condenser 24 where they are suitably condensed and the distillate is then stored in and forced by the pump 42 into the still 11 which may be maintained at a temperature of approximately TSQ to 800 F. and a pressure of about 200 lbs, which temperature and pressure are substantially greater than those maintained in still 10 and more suitable to bring about the cracking of some of the higher boiling fractions. The vapors evolved in still 11 pass to the separating device 19 and the condensate formed therein, substantially all of which distills within the limits of kerosene, while Sl'lll hot, passes through the insulated pipe 40 and is forced by pump 43 into the still 12 which is maintained at a still higher temperature and pressure than any of the preceding stills in the series. In this still the temperature may, for example, be maintained at from 810 to 850 F. and the pressure at approximately 300 lbs. or higher. At this increased temperature and pressure cracking of the kerosene fractions takes place and the vapors are separated in the manner already described in connection with stills l0 and 11 and certain of the lower boiling gasoline- ]ike fractions are drawn off for condensation and collection, while the higher boiling fractions, if there be any at this stage, are subjected" to further cracking at increa ed temperatures and 'n'essures in additional stills. The number of cracking zones or stills required to obtain the maximum quantity of condens'able light oils depends largely upon the character of the oil charged into the apparatus and upon the degree of cracking which has taken place in the preceding stills, and it is, therefore, apparent that the number of stills to be employed may be increased or decreased according to attendant conditions and requirements.

It will be understood from the foregoing that in each successive step the condensate, while still hot, is drawn oil fronrt-he separating device .through insulated piping, which prevents loss of heat therefrom. and pumped into the next still of the series. By preventing loss of heat from the condensate less external heat is required to maintain .the oil at the desired cracking temperatures in the several stills and a considerable saving is thereby effected.

It is likewise apparent that in each suc cessive step of the process the vapors evolved in the different, stills are separatedin the separating devices according to their bOlling points, the lower boiling fractions, stillin the form of vapors, being led off to a condenser, and thehigher boiling fractions, in the form of hot condensate, being immediately subjected to further cracking atan increased temperature and pressure. Thus, at least, a portion of the vapor derived from any one of the stills is drawn off and conmaximum benefit from the equipment, if

the stills are all of substantially the same size, it may be desirable to'introduce' fresh supplies of oil of predetermined characteristicsto each still to augment the supply of hotcondensate and compensate for the fractions taken off from the preceding still. On the other hand, it may be desirable to provide stills of varying sizes adapted to handle charges of ditferent volumes.

In order that. additional oil of suitable characteristics may be charged into the system during a run, a crude still 44 is provided which is heated in any well-known manner. The 'apor portion of the still is connected by means of a suitable insulated pipe or line 45 to one of a series of fractional condensers 46, 47 and 48, each of which is connected by an insu ated line or pipe, as 49, 50 and 51 to one of the cracking stills. Each of thelines referred to connects the condensateretaining portion of one of the condensers with one of the cracking stills and a pump 52 is placed in each of the lines for forcing the condensate into the still against; the pressure maintained therein. The vapor portion of each of the fractional condensers 4G and 47 is connected by means of a suitable insulated line or pipe as 53 and 54, respectively, with the next succeeding condenser in the series so that the separated vapor in each condenser passes on to the next condenser of the series for further separation. tional condenser of the series, in this particular instance 48, are passed through a suitable final condenser 55 and the distillate is stored in a tank 50 or drawn off to be otherwise disposed of. I

Another branch pipe or line 57 is provided which connects the lines 49, 50 and 51 with the 'apor portion'ofthe independent crude still 44, and suitable valves, such as 58, are provided and arranged in the several The vapors from the last frac 4o ically, as may be desired, charged into the several cracking stills to augment the supply 1 of hot condensate and thus take the place lines so that the'condensate formed in each of the fractional condensers 46, 47 and 48 can beeither returned directly to the crude still or. charged into the cracking stills with which the' particular condenser is directly connected by means of the insulated pipes 49, 50 and 51, respectively. Thus it will be seen that by proper manipulation of the valves 58 in the several lines, the crude still 44 can be operated to provide additional charges of oil for replenishing the several cracking stills of the series. By proper design or control of the fractional condensers 46, 47 and 48 the condensates formed therein may be of substantially the same characterlas being charged into the respective stills with which the several fractional condensers are connected.

By reason of this arrangement, the crude still may be operated concurrently with the cracking stills 10, 11 and 12, whereby the -vapors evolved in the crude still will be passed, first through-the condenser 46 wherein there is a separation of the high and low boiling fractions, the high boiling fractions condensing and being charged directly into the still 10 through the insulated line'49. The lower boiling fractions will flow through the insulated line 53 to the condenser 47 wherein further separation will take place, the low boiling fractions again being separated from the, high boiling frac- 'densers tions. The high boiling fractions are charged from the condenser 47 into the cracking still 11, andthe low boiling frac-- tions pass in the form of vapor to the next condenser 48 of the series wherein further separation and distribution of the high and low boiling fractions takes place. In this manner fresh oil is continuouslyor period.-

of the lighter fractions which have previously been separatedand passed ofi as before for further condensation. The fresh oil so charged into the several cracking stills is of sufiiciently the samecharacter as the oil already in the stills that the mixtures thereof may be effectively converted under the cracking conditions of progressively increasing pressure and temperature obtaining in the series of stills. a

Of course, it is understood that instead ,of providing the crude still 44 and the condevices such, for example, as bubble towers connected in series might be connected to one of; the cracking stills of the series as,

for example, to still 10. The heavy back trap from the first of theseparating devices of this relatively low pressure. unit could then be charged into the still 11, and the backstrap or condensate of lighter gravity from the second separating device could be 46, 47 and 48, a pair of separating and scope of the invention defined in the appended claims.

\Vhat I claim is:

1. The process of converting heavy hydrocarbon oils into oils of lower boiling point] which comprises subjecting oil to a cracking temperature and pressure in a pressure zone, separating the high boiling fractions of the evolved vapors from the low boiling fractions in the formof a condensate, then subjecting the condensate while still hot to increased cracking temperature and pressure, simultaneously distilling another independent body of oil, separating the evolved vapors according to their boiling points, and co-mingling the condensate thus formed with the oil in one of the pressure zones.

2. Apparatus for converting heavy hydrocarbons into oils of low boiling point comprising, a plurality of stills maintained at successively increased temperatures, and pressures, a separating device connected to each of said stills, means connecting each of said separating devices with the next succeeding still, means for forcing-the condensate of each separating device into the next succeeding still, and independent means for charging additional oil to each of said cracking stills including a crude still, a plurality of fractional condensers connected in series therewith and means severally connecting each of said condensers with one of said pressure stills for supplying the condensate from each condenser to the still with which it is connected.

3. The process of converting heavy hydrocarbon oils into oils of lower boiling point which comprises, subjecting oil to a cracking temperature and pressure in a pressure zone, separating the high boiling fractions of the evolved vapors from the lower boiling fractions in the form of a condensate, subjccting the condensate while still hot to inincreased cracking temperature and pressure, simultaneously distilling another independgo ent-body of oil, passing the evolved vapors through a pluralit of fractionating devices to separate t em accordin to their boiling points, and co-mingling t e condensates thus formed in each of the fraction- 1 5 ating devices with the oil in one of the pressure zones. I

4. The process of converting heavy hydrocarbon oils into oils of lower boiling point which comprises subjecting oil to a cracking temperature and pressure in a pressure zone, separating the high boiling fractions of the evolved vapors from the lower boiling fractions in the form of a condensate, subjecting the condensate While still hot to increased cracking temperature and pressure,

simultaneously distilling another independcnt body of oil, separating the evolved vapors according to their boiling points, charging the condensate thus formed While still hot into 'one of the pressure zones to co-mingle with the oil therein, and subjectpcratures'and pressures, a separating device connected to each of said stills, means con-' necting each of said separating devices with the next succeeding still, means for charging the condensate of each separating device into the next succeeding still, anindependent still, a plurality of means connected with said still for successively sepameans for charging the separate condensates so formed, while still hot, into the different pressure stills for further treatment therein.

6. The process of converting heavy hydrocarbons into oils of low boiling point which comprises subjecting oil to a temperature and pressure suflicient to effect cracking thereof, separating the high boiling fractions of the evolved vapors from the low boiling fractions in the form of condensate, forcing the condensate so separated into a succeeding zone for further cracking at an increased temperature and pressure, and mixing with the condensate an additional charge of preliminarily treated oil having substantially the same characteristics as the condensate with which it is mixed;

In witness whereof I have hereunto set my hand'this 23rd day of October, 19:24.

GEORGE WILLIAM GRAY.

DISCDLAI MER- 1,724,'760.Ge0rge William Gray, New York, N.-Y. PRocEss AND APPARATUS For.

THE CRACKING OF HY'nRocARBoN OILS. Patent dated August 13,1929. Disclaimer filed November 10, 1931, by the assignee, The Texas Company.

Hereby enters this disclaimer to claims 1, 3 and 4 of the aforesaid Letters Patent which are in the following words', to wit: 7 p

,1. The process of converting heavy hydrocarbon oils into 0113 of lower bo ling point which comprises subjecting oil to a cracking temperature and pressure in a pressure zone, separating the high boiling fractions of the evolved vapors from the low boiling fractions in the form of a condensate, then sub eeting the condensate while still hot to increased cracking temperature and pressure, simultaneously distilling another independent body of oil, separating the evolved vapors. according to their boiling points, and cormingling the condensate thus formed with the oil in one of the pressure zones.

53. The process of converting heavy hydrocarbon oils into OllS of lower bo ling point which comprises, subjecting oil to a cracking temperature and pressure inha pressure zone, separating the high boiling fractions of the evolved vapors from t le lower boiling fractions in the form of a condensate, sub ecting the condensate whi e still hot to increased cracking temperature and pressure, simultaneously distilling 7 another independent body of oil, passing the evolved vapors'through a plurality of fractionating, devices to separate them according to their boiling points, and comingling the condensate thus formed in each of the fractionating devices with the oil in one'of the pressure zones.

The process of converting heavy hydrocarbon oils into oils of lower boiling point/which comprises, subjecting oil to a cracking temperature and pressure in a pressure z one, separating the high boihng fractions of the evolved vapors from the lower boiling fractions inithe form of a condensate, subjecting the condensate while i still hot to increased crackingtemperature and pressure, simultaneously distilling another inde endent body of oil separating the evolved vapors according to their boiling points, charging the condensate thus formed whileetill hot into one of the pressure zones to co-mingle with the oil therein, and sub ecting the remaining-vapors while still hot to further fractionation to form additional condensate for the next succee pressure zone." a

[ Gazette December], 1931 .1 i 

